I've recently completed a 5F1 inspired amp. I've build a couple hifi tube amps before, but this is my first guitar amp. It's based on the 5F1 but with some modifications inspired by different sources, eg. Rob Robinette's site. Cabinet, chassis and turret board is all homemade. The speaker is a Jensen P10R.
Power supply: The HT mains transformer is from Primary Windings and has a single 250V winding so I'm using a silicon bridge rectifier. I have added an extra CR filter so power to the output tubes is filtered.
Grounding: I use the preamp / power section grounding scheme
Preamp: I have added a bypass cap on V1 and only have 1 input jack with a 33K grid stopper. I have added a framus mid control.
NFB: I have a switch so I can choose between 10K or 22K negative feedback